questions 6

Clostridium tetani

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Topic updated on 10/31/16 9:13am

Snapshot
  • A 40-year-old man presrisus sardonicus seen in tetanusents to your clinic with a 3-day history of jaw discomfort and inability to open his mouth. Ten days ago he had punctured his right foot with a nail while working in his shed. He did not seek medical attention. Patient was immunized in childhood but had never received a booster dose since then. Temperature was 98.4°F (37°C) and blood pressure was 120/70 mmHg. Physical exam revealed an inability to open his mouth more than one inch as well as a puncture wound on the sole of the left foot 2.5 cm by 1 cm, with surrounding erythema. Patient was admitted and given two doses of hyperimmune tetanus immunoglobulin as well as one dose of Td booster. Intravenous metronidazole as well as diazepam was given and wound debridement was carried out.
Introduction
  • C. tetaniClassification
    • bacteria (anaerobic)
      • gram-positive bacilli
        • spore-forming
          • Clostridium
            • C. tetani
  • Pathogenesis
    • transmission
      • puncture wounds/trauma
        • requires low tissue oxygenation
      • mothers
        • incompletely removed placentas
      • neonates
        • colonization of umbilical stump
    • reservoir
      • soil
    • molecular biology
      • spores germinate in tissues and produce exotoxin
      • exotoxin travels to the CNS by retrograde axonal transport
        •  binds to ganglioside receptors
        •  cleaves SNARE protein at pre-synaptic nerve terminals
        •  blocks glycine release from Renshaw cells in spinal cord
          • glycine is  an inhibitory neurotransmitter
Presentation
  • Tetanus
    • caused by tetanospasmin toxin
      • prevents release of inhibitory neurotransmitters glycine and GABA in the spinal cord
      • the cleavage of synaptobrevin 2 halts the fusion of the vesicle with the neuronal membrane  
      • travels to CNS by retrograde axonal transport
    • tetanic (spastic) paralysis
    • risus sardonicus
    • trismus (lockjaw)
    • opisthotonus
Evaluation
  • Large gram-positive, spore-forming rods
    • "tennis racket" appearance
  • Diagnosis is clinical on the basis of history and physical exam
    • organism is not usually isolated
Differential
  • Seizure disorders
  • Meningitis
  • Trismus secondary to dental infection
  • Drug-induced dystonias
Treatment
  • Vaccine
    • made of tetanus toxoid
      • formaldehyde-inactivated
    • prevent neonatal tetanus by vaccinating women of childbearing age 
    • babies first administered vaccine at 2 months of age
  • Post-exposure
    • hyperimmune human globulin (TIG) neutralizes toxin
    • metronidazole or penicillin also given
    • spasmolytic drugs treat symptoms (e.g., diazepam)
Prognosis, Prevention, and Complications
  • Prognosis
    • worse in
      • generalized tetanus
      • extremes of age
      • poor access to intensive medical care
  • Prevention
    • universal vaccination with DTap beginning in infancy
    • booster doses are given
      • every 10 years in adults
      • third trimester of pregnancy
      • following puncture wounds if immune status uncertain
  • Complications
    • laryngospasm
    • fractures
    • respiratory failure and death


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Qbank (6 Questions)

TAG
(M1.MC.1) A 71-year-old male is brought to the emergency room by his caretaker and presents with difficulty breathing, muscle rigidity in the face, neck, back and upper extremities, and profuse sweating. The intern notes a large wound on his head near the back of his right ear which his caretaker had bandaged up. The caretaker explains that the wound was the result of a fall while walking in his backyard. The intern performs a quick physical exam and observes increased reflexes. The patient was intubated to assist in his breathing and was given diazepam, metronidazole, and an immunoglobulin after the blood work came back. Which of the following neurotransmitters is affected in this patient? Topic Review Topic

1. Glycine
2. Acetylcholine
3. Dopamine
4. Epinephrine
5. Serotonin

PREFERRED RESPONSE ▶
TAG
(M1.MC.1) A 9-year-old female child whose family recently emigrated from Afghanistan presents to the county hospital with difficulty swallowing and generalized muscle rigidity. Her parents note that although she is in severe pain she always appears to be smiling. After getting a detailed history from the parents, the residents comes to the conclusion that the child's clinical presentation is due to a lack of immunizations and a deep wound on her knee resulting from a fall six days ago. Which of the following is the mechanism of action of the toxin causing this child's symptoms? Topic Review Topic

1. Inhibiting protein synthesis via ADP-ribosylation of elongation factor 2
2. Overactivating adenylate cyclase by ADP-ribosylation of the Gs alpha subunit
3. Overactivating adenylate cyclase by disabling the Gi subunit
4. Preventing release of GABA by cleaving of synaptobrevin 2
5. Preventing release of acetycholine by cleaving SNAP-25

PREFERRED RESPONSE ▶
TAG
(M1.MC.11) A 1-week-old infant that was birthed at home is rushed to the emergency room by his parents. His parents are recent immigrants who do not speak English. Through a translator, the child's parents say that during play with the infant, the infant's body became rigid and his mouth 'locked up'. The child likely suffered from a(n): Topic Review Topic

1. Infection of a foot ulcer
2. Infection of the colon
3. Intrauterine infection
4. Infection of the umbilical stump
5. Dental infection

PREFERRED RESPONSE ▶
TAG
(M1.MC.22) A 45-year-old Caucasian male presents complaining of inability to open his mouth. Patient history reveals that he recently injured his foot from an exposed floor nail in his house. This patient's symptoms are likely the result of: Topic Review Topic

1. Impaired motor neuron release of ACh
2. Impaired motor neuron release of GABA
3. Increased production of gas in his soft tissues
4. Cross-reactivity of bacterial antigens
5. Bacterial infiltration of the central nervous system

PREFERRED RESPONSE ▶
TAG
(M1.MC.74) A one-week-old boy is brought to the emergency department by his mother, who recently immigrated to the United States and does not have health insurance. He was born at home, and has not received any medical care since birth. The mother states the boy has become irritable and has been feeding poorly. In the last day, she said he seems "stiff" and is having apparent muscle spasms. On your exam, you note the findings in figure A. Which of the following interventions might have prevented this disease? Topic Review Topic
FIGURES: A          

1. Conjugated polysaccharide vaccine given to infant at birth
2. Toxoid vaccine given to mother pre-natally
3. Vitamin injection given to newborn at birth
4. Improved maternal nutrition
5. Genetic counseling

PREFERRED RESPONSE ▶
TAG
(M1.MC.74) A 6-year-old boy who recently immigrated to the United States is brought to the emergency department by his mother. His mother states that the boy had a deep cut several days ago, which she thoroughly washed and bandaged at home. He has now been having severe muscle spasms. When you examine the boy, you note the findings shown in Figure A. Which of the following best describes the pathological mechanism behind the boy's presentation? Topic Review Topic
FIGURES: A          

1. Inactivation of elongation factor
2. Increase in cyclic AMP
3. Destruction of protein leading to inhibition of neurotransmitter release
4. Destruction of cell membranes
5. Massive release of cytokines

PREFERRED RESPONSE ▶


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